A variety of circuit devices employ a variety of semiconductor integrated circuits, such as LSIs (Large Scale Integrated Circuits) or VLSIs (Very Large Scale Integrated Circuits). The semiconductor integrated circuits each include a data bus for transmitting data signals and an address bus for transmitting address signals, and also have a plurality of data pins connected to the data bus and a plurality of address pins connected to the address bus.
When a plurality of semiconductor integrated circuits are interconnected in use, data pins are connected to corresponding data pins, and address pins are connected to corresponding address pins among the plurality of semiconductor integrated circuits.
A semiconductor storage has recently been proposed, which provides a selective connection of each external pin to an address bus, data bus, or control bus, by means of a switching circuit (refer to JP 8-221977 A, for example). This allows the function of each external pin to change.
If a third party knows the arrangement of data pins in each of a plurality of interconnected semiconductor integrated circuits, the person can pull out data signals on a data bus using a commercially available tool, to easily load into another storage. This makes it difficult to ensure data security. Digital video or audio data in particular do not degrade in quality by duplication, and therefore, it is easy to illegally copy high-quality video or audio data.